Ch. 11 & 3 IMF & stoichiometry test [95 points] AP Chem
For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.
Academic Honesty: The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus. I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam. If you violate any of the preceding items or do not sign, your semester grade is a F.
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1. What is the % yield in the reaction: 5.0 g C2H6 + 15.0 g O2 à CO2 + 5.0 g H2O ? [20 points]
2. 1.00 g CxHyOz + excess O2 à 2.00 g CO2 + 0.818 g H2O. [20 points]
a. What is the empirical formula of the compound ?
b. The molar mass of the compound is 88 g / mole; what is its chemical formula ?
3. What is the relative vapor pressure of HCl versus HBr ? Justify your response. [hint: this is a “trick” question; 10 points]
4. Which compound, carbon tetrachloride versus carbon tetrabromide, would have the larger boiling point ? Justify your response; use and define the term, polarizability, in your response. [15 points]
5. Describe the graphical analysis to determine the enthalpy of vaporization, ΔHvap, using the Clausisus-Clapeyron equation
state the experimental data needed in such an analysis. [10 points]
6. Sketch the vapor pressure versus temperature graph for dimethyl ether (i.e. ether with 2 methyl groups) versus ethyl alcohol (i.e. alcohol with an ethyl group); put both curves on the same graph; identify the curve for the ether versus alcohol. Justify your response. [20 points]